Neutralization of HPV16, 18, 31, and 58 pseudovirions with antisera induced by immunizing rabbits with synthetic peptides representing segments of the HPV 16 minor capsid protein L2 surface region

Neutralizing antibody against human papillomavirus (HPV) minor capsid protein L2 can cross-neutralize different HPV genotypes in vitro. To identify the segments containing the cross-neutralization epitopes of HPV 16 L2, we characterized antisera obtained by immunizing two rabbits with each of the ten synthetic peptides of 14 to 20 amino acids (aa) long, which represents a part of the HPV 16 L2 sequence from as 14 to 144. The antisera against the peptides within the region from as 18 to 144 efficiently bound to HPV 16 L1/L2-capsids and neutralized HPV 16 pseudovirions, indicating that the region is displayed on the surface of the capsids and contains several neutralization epitopes. Antiserum against the peptide from as 18 to 38 (anti-P18/38) cross-neutralized HPV 18. Anti-P56/75 cross-neutralized HPV18, 31, and 58. Anti-P61/75 and anti-P64/81 cross-neutralized HPV 18 and 58. Anti-P96/115 and the antiserum induced by a mutant P96/115 (S and T at as 101 and 112 were replaced with L and S, respectively) cross-neutralized HPV31 and 58. The mixture of equal volumes of three antisera, anti-P18/38, anti-P56/75, and anti-mutant P96/115, neutralized HPV 16, 18, 31, and 58 more efficiently than anti-P56/75 alone, suggesting that there is a synergistic effect of antibodies on the cross-neutralization. The cross-neutralization appears to be correlated with conserved as sequences among HPV types. The data in this study provide a basis for designing vaccine antigens effective against a broader spectrum of the high-risk HPVs. (c) 2006 Elsevier Inc. All rights reserved.